The shirt fits snugly which took a little getting used to.  It is really nice to have the rear pockets, sun protection on my arms, and cooling effect, though.  This shirt cools much better than I expected.  On my first run, an 85' F day, I was even a little cool during a breezy section going over a bridge.  I've worn it in the water, and amazingly it stays put and stays snug.  I can't wait to use it on race day.